RadioCompass

Introduction

The main objective of the RadioCompass project has been to develop and test an innovative system for the purpose of high-precision/high-integrity train navigation and attitude determination.

These high-performance requirements are necessary in applications such as track maintenance, measurement of track curvature, power supply diagnosis and safety-related applications. RadioCompass integrates the best sub-modules available on the market and can be used as a benchmark for other equipment.

Moreover, in combination with the modularity concept, the RadioCompass prototype offers the possibility to react flexibly on new objectives by up or downgrading the equipment’s performance according to the user’s needs, to implement newly developed components, or to use the unit for new types of satellite navigation signals.

Applications

The main applications of RadioCompass are going to be in the Rail domain with particular interest in high-precision train navigation and attitude determination for safety-critical applications.

Technical Performance

All functional and performance objectives of the RadioCompass prototype specification have been achieved. This was mainly due to the fact that the system has been subject to a rigorous standard engineering procurement and has been successfully tested and subsequently integrated on different levels from component to the full-blown device. The complete functionality has been approved during environmental testing, and the full performance in terms of 3-D position and attitude accuracy has been verified during:

acceptance testing on a dedicated transporter car on a known route

application testing on a rail vehicle in usual day-to-day operations on commercial tracks.

The system performance has been approved by computing the position and attitude residuals with respect to dedicated reference data, which were recorded online by a geodetic dual-frequency GNSS reference station and a Sigma30 INS reference attitude system, which was mounted onto the test vehicles alongside the RadioCompass device.

Control of the RadioCompass functionality, monitoring of the real-time performance of the moving RadioCompass and information about the current status and performance of the individual sensors (integrity) was carried out using a dedicated graphical user interface, the so-called QuickLook Monitor.

The following tables summarize the performance values obtained during the rail tests.

Standard deviation

Latitude [m]

4.179

Longitude [m]

3.661

Height [m]

4.621

North [m/s]

0.383

East [m/s]

0.186

Down [m/s]

0.308

Roll [deg]

0.232

Pitch [deg]

0.108

Yaw [deg]

1.379

In summary, the selected configuration of the RadioCompass, in particular the core sub-systems Novatel Millenium GNSS receiver and Litton LN-200 IMU, the implemented Kalman data filter and the real-time QuickLook monitor, proved to fulfill the target performance specification completely. The design is modular, but at the same time very robust, and the implemented filter is able to stabilize and smooth the GNSS position solution significantly at GNSS outage conditions. The system attitude shows a complementary characteristic, which is mainly due to the excellent performance of the IMUs gyroscopes.

Commercial Outlook

As can be derived from the achieved performance results, the RadioCompass system basically offers a variety of different fields of application to be exploited further. This is mainly due to the two major features of the system:

the generation of precise attitude data

the capability to maintain the knowledge about current position (and attitude) even under blockage or complete absence of satellite signals, e.g. in tunnels.

The combination of IMU and GNSS-based measurements via a robust Kalman filter is able to stabilize the entire system significantly and makes it less sensitive to external influences. This gives the system various interesting technical and commercial prospects.

In combination with the modularity concept, the RadioCompass prototype offers the possibility to react flexibly on new objectives by up- or downgrading the equipments performance according to the users needs, to implement newly developed components for one of the modules potentially leading to further miniaturization if wanted, or to use the unit for new types of satellite navigation signals as in the very near future with Galileo.

But, also in its less compact outer shape as realized now, the equipment is usable for a variety of applications which do not exhibit strong restrictions in size, weight, or power consumption. This is especially true for any heavy cargo transportation system like large overland trucks, container ships, the logistics systems in harbors or railway stations. Also special or precious cargo transport carriers such as tank wagons for chemicals and fuels should be an interesting market for such combined positioning/velocity/attitude device as the RadioCompass.

This might become particularly true if these systems operate with cargo loading and de-loading devices which not only move laterally but are subject to rotational movements which have to be precisely monitored.

In summary, the RadioCompass prototype has the potential to serve as a core element of an enhanced product line at Kayser-Threde and to serve at the same time as a practical test platform for exploiting further European satellite navigation technology and attitude sensors, both at Kayser-Threde and IfEN. All in all, it seems to be a realistic approach to open up whole new markets with this flexible, innovative, highly precise and powerful navigation device.

Schedule

RadioCompass started in January 2001 and the design was completed by January 2002. The project ended in September 2003.

Consortium

The project has been developed by Kayser-Threde GmbH (Germany) in partnership with IfEN GmbH (Germany).